The present invention relates generally to welding systems and materials, and more particularly to a system and method to facilitate fillet weld performance in gas metal arc welding systems by controlling a toe angle, toe radius, and penetration depth of the weld.
Welding systems reside at the core of the modem industrial age. From massive automobile assembly operations to automated manufacturing environments, these systems facilitate joining in ever more complicated manufacturing operations. One such example of a welding system includes a gas metal arc welding system (GMAW). This may involve movement of a consumable electrode, for example, toward a work piece while current is passed through the electrode and across an arc developed between the electrode and the work piece, wherein portions of the electrode may be melted and deposited on the work piece. Other aspects of the welding system relate to control of power and waveforms supplied to the electrode, movements or travel of a welding tip during welding, electrode travel to other welding points, gas control to protect a molten weld pool from oxidation at elevated temperatures and to provide ionized plasma for an arc, for example, and control of arc stability to control the quality of the weld.
Several other factors influence the quality, stability, and performance of the weld, wherein subsequent processing to improve these factors can significantly impact the cost of a joining operation. As an example, non-load carrying fillet welds are often employed to join a non-load carrying structural member to a second structural member that are often joined at right angles between the members. Some of the factors that contribute to the fillet weld quality include a toe angle and toe radius that are defined at the junction of the toe of the weld and the member, along with a throat dimension and penetration depth defining how much of the weld overlaps and subsequently penetrates the material of the members. For example, many high-performance conventional welds provide a toe radius of about one millimeter or less. Unfortunately, weld fatigue failures usually occur at the weld toe on the non-load carrying member. These fatigue failures can be caused by a sudden geometry change between the member and weld toe intrusions, for example. Fatigue life of the weld can be compromised by the weld toe intrusions in addition to sharp notch effects that may appear in conventional welds. This can include such imperfections as undercut, slag entrapment, and/or other discontinuities in the weld.
In order to improve fillet weld quality, many conventional welding systems and processes utilize post-weld techniques that can mitigate some of the problems described above. These processes can include weld toe grinding, plasma dressing, hammer peening, shot peening, bur grinding, water-jet processing, disc grinding and/or combinations thereof to attempt to mitigate intrusions or other imperfections and ultimately improve the fatigue life of the weld. Manufacturers that rely on such welding techniques also often have to design according to much more rigid standards. This may include incorporation of thicker materials in order to reduce the stress range at the weld connection. As can be appreciated however, utilizing one or more post-processing techniques and/or incorporating thicker materials to improve weld performance can substantially influence the cost of welding in general and the overall assembly process in particular.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the present invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention relates to a system and method to facilitate fillet weld performance. This is achieved by analyzing and controlling a plurality of factors that individually, collectively and/or combinations thereof increase the fatigue life strength and quality of the weld and mitigate weld post processing. Thus, manufacturers can reduce the thickness of load-carrying members, and/or increase weld fatigue life of existing members and design to less conservative standards thereby reducing costs in welding operations. One such factor is to determine and control one or more welding parameters that influence the fillet weld process. These parameters can include wire feed speed, travel speed, and part angles in the deployment of the weld, for example. Another factor is to control the surface conditions of the members to be joined such as controlling the smoothness of the respective surfaces. Yet another factor includes determining the effects of various weld alloys and selecting alloy combinations that yield improved weld performance while mitigating the need to further process the weld such as removing toe intrusions and notches from the weld. Another important factor relates to controlling shielding gas mixtures to improve both horizontal and angled welding operations.
In accordance with the present invention, weld processing factors are determined and affects associated therewith are analyzed. Weld geometries are then profiled and optimized to facilitate improved performance. This includes minimizing weld toe intrusions and post processing, for example. One or more welding variables such as wire and travel speed are determined and controlled. Weld member surface conditions can be controlled via basted plate and/or blasted strip techniques, for example. Wire alloy processing is controlled to include a process, wherein sulfur content along with other elements are maintained in a defined range to improve weld performance. Shielding gas components such as oxygen, argon, helium and carbon dioxide are also controlled in one or more combinations to similarly improve the weld. Improvements can be realized in the resultant geometry of the fillet weld by utilizing one or more of the processes described above and/or combinations thereof. These improvements can include increasing the toe angles and radius associated with the weld while maintaining weld throat and penetration depth dimensions. By controlling these dimensions, fatigue life of the weld can be substantially improved while maintaining strength in addition to mitigating the need to further process the weld thereby reducing costs in the overall design, welding and assembly process.